Recycled basalt fiber-carbon nanotube/epoxy composite with piezoresistive behavior for strain and damage self-sensing

The growing concern for the environmental has boosted the use of recycled fibers for second life applications. However, achieving recycled fiber reinforced polymers with good mechanical performance remains challenging. Herein, basalt fiber (BF) fabrics were first recovered via solvolysis using hydrogen peroxide and then spray-coated with multiwalled carbon nanotubes (MWCNTs). The resulting recycled BF fabric after spray-coating showed a remarkable reduction in electrical resistance (22.5 kΩ) and a homogeneous coverage distribution of MWCNTs onto their fiber surface. The BF fabrics modified with CNT were used to manufacture recycled basalt fiber reinforced polymer with MWCNTs (BFRP-CNT) by vacuum assisted resin infusion technique and then cut into beam specimens for electromechanical flexural testing. The piezoresistive characterization showed that the change in electrical resistance of the recycled BFRP-CNT composite followed the flexural stress-strain response until composite’s failure and yielded gage factor value of 7.31 for the tensile side and −1.01 for the compressive side, confirming its piezoresistive sensing capability. The findings suggest that the developed recycled BFRP-CNT composite holds promise as an environmentally sustainable material suitable for strain monitoring and damage sensing through the piezoresistive response obtained during monotonic three-point bending up to failure.